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Quick Consult: Symptoms Pruritic, Burning Rash

Dr. Wiler is an assistant professor of emergency medicine and the vice chair of clinical quality, patient safety, and process improvement at the University of Colorado Denver School of Medicine and an adjunct assistant professor of emergency medicine at the Washington University School of Medicine in St. Louis.

A 49-year-old man presents with a rash he has had for two days. He is concerned that he was exposed to poison sumac after clearing brush in his backyard. He denies any fever, chills, or eye drainage. The rash is slightly pruritic and “burns.”

Shingles affects as many as one in every 278 U.S. adults per year with more than 92 percent having no identifiable immunocompromising condition. (Mayo Clinic Proc 2007;82[11]:1341.) The lifetime risk of developing shingles for those over 85 is 50 percent, but recurrent events in immune-competent persons is uncommon. (JAMA 2009;302[1]:108.) Approximately one million cases of shingles are diagnosed in the United States each year. (JAMA 2011;305[2]:212.) Risk factors besides age over 50 and immunosuppression are unknown for this condition.

Herpes zoster ophthalmicus classically presents with vesicular lesions on the face in the cranial nerve five (trigeminal) ophthalmic distribution. A prodrome of generalized malaise, fever, headache, fatigue, chills, and a burning or tingling pain may precede the rash by up to five days. Classically, the rash is unilateral and in a dermatomal distribution; most commonly it affects only the upper eyelid. The rash begins as maculopapular lesions followed by a cluster of clear vesicular blisters on an erythematous base. The lesions evolve over three to five days, and can coalesce into larger lesions that progress into pustules and eventually open and crust over. Rash sensations can range from pruritic to painful. Acute pain occurs in 95 percent of patients, with nearly half reporting severe pain.

Herpes zoster ophthalmicus is distinct from herpes simplex viral infection (HSV) keratitis. The pathognomonic lesion of HSV keratitis is a dendritic lesion with skin lesions that do not respect the midline. (Wills Eye Manual, p. 60.) Herpes zoster ophthalmicus, however, can be associated with unilateral pseudodendrites.

Zoster is typically a clinical diagnosis because the rash has characteristic features, but direct fluorescent antigen assay or DNA polymerase chain reaction techniques are superior to culture if laboratory confirmation is required. (JAMA 2009;302[1]:108.)

Early diagnosis, treatment, and ophthalmologic evaluation are prudent to prevent corneal involvement, impairment, or loss of vision. Treatment of herpes zoster ophthalmicus includes oral antiviral agents (acyclovir, famciclovir, valacyclovir). This can shorten the duration of symptoms, decrease the severity of infection, and decrease the duration of pain (acyclovir only per Cochrane DatabaseSys Rev 2009;[2]:CD006866) if taken within 72 hours of symptom onset. Supportive care is the mainstay of treatment otherwise. This includes bacitracin ointment to skin lesions bid and warm skin compresses to the affected area (to keep clean). Treatment of iritis/intraocular inflammation includes topical steroids and a topical cycloplegic eye drop. Corneal lesions are treated with erythromycin ophthalmic ointment bid.

Adequate pain control can be challenging in the immunosupressed or elderly patient. Long-acting opioids are preferred to short-acting ones, and non-opioid analgesics can also be effective, including gabapentin (Neurontin), tricyclic antidepressants, and pregabalin (Lyrica).

Patients should be told to keep weeping lesions covered because others not previously exposed to VZV are susceptible and to prevent scratching lesions, which can become secondarily infected or scar. Good hand hygiene is also recommended. The contagious phase is complete once lesions are completely crusted over. (JAMA 2011;305[2]:212.) Total healing takes approximately two to four weeks, and residual scarring can occur.

The most common complication of shingles is post-herpetic neuralgia, defined as pain persisting at 120 days after disease onset. Persistent pain of more than a month is reported in nearly 70 percent of patients over 50. (JAMA 2009;302[1]:108.) Secondary skin infection is a rare but noted complication of shingles, occurring in approximately two to three percent of cases. Encephalitis, pneumonia, myelitis, granulomatous arthritis, herpes gangrenosum (herpetic necrotizing fasciitis), cranial and peripheral nerve palsies are rare complications of shingles infections. (JAMA 2009;302[1]:108.)

The FDA approved the Oka varicella vaccine for administration in children (19 to 35 months) in March 1995. This helped decrease the incidence of primary varicella infection, but was not adequate to prevent shingles in those previous inoculated. The Zostavax vaccine was approved in 2006 for those 60 and older to prevent zoster infection. This is a live attenuated vaccine and not recommended for patients who are pregnant, under 12 months old, or immunocompromised. (MMWRRecomm Rep 2008;57[RR-5]:1.) This vaccine does not prevent infection but prevents reactivation of the latent virus by suppression because only those who have previously been infected with VZV can get shingles. It has been shown to reduce the incidence of infection by more than 50 percent. (JAMA 2011;305[2]:160.) It also reduces the incidence of long-term VZV-related neuropathic pain (67%), VZV-associated hospitalizations (J Infect Dis 2008;197[6]:825), and ophthalmic herpes zoster. (JAMA 2011;305[2]:160.)

This patient was discharged on oral antivirals, erythromycin ophthalmic ointment, and analgesia with follow-up the next day with ophthalmology.

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